Application of coordinate transformation to two-dimensional scattering and diffraction problems

1969 ◽  
Vol 47 (7) ◽  
pp. 795-804 ◽  
Author(s):  
L. Shafai
Keyword(s):  
Electromagnetic Field ◽  
Differential Equations ◽  
Cross Section ◽  
Coordinate Transformation ◽  
Scattered Field ◽  
Arbitrary Cross Section ◽  
Surface Currents ◽  
Two Dimensional ◽  
Dimensional Problem ◽  
First Order

The two-dimensional problem of determining the electromagnetic field scattered by a cylinder of arbitrary cross section is reduced to the solution of first-order, coupled differential equations. The procedure for finding the surface currents, scattered field, and the scattering cross section for a perfectly-conducting cylinder is given in detail. A brief study of the scattering by a polygonal cylinder and n identical strips equally spaced azimuthally around the z axis is used to examine the behavior of the differential equations.

scholarly journals Signal Propagation in Soil Medium: A Two Dimensional Finite Element Procedure

2021 ◽  
Author(s):  
Frank Kataka Banaseka ◽  
Kofi Sarpong Adu-Manu ◽  
Godfred Yaw Koi-Akrofi ◽  
Selasie Aformaley Brown
Keyword(s):  
Finite Element ◽  
Cross Section ◽  
Scattered Field ◽  
Radar Cross Section ◽  
Transverse Magnetic ◽  
Arbitrary Cross Section ◽  
Observation Angle ◽  
Two Dimensional ◽  
Total Field ◽  
Dimensional Finite Element

A two-Dimensional Finite Element Method of electromagnetic (EM) wave propagation through the soil is presented in this chapter. The chapter employs a boundary value problem (BVP) to solve the Helmholtz time-harmonic electromagnetic model. An infinitely large dielectric object of an arbitrary cross-section is considered for scattering from a dielectric medium and illuminated by an incident wave. Since the domain extends to infinity, an artificial boundary, a perfectly matched layer (PML) is used to truncate the computational domain. The incident field, the scattered field, and the total field in terms of the z-component are expressed for the transverse magnetic (TM) and transverse electric (TE) modes. The radar cross-section (RCS), as a function of several other parameters, such as operating frequency, polarization, illumination angle, observation angle, geometry, and material properties of the medium, is computed to describe how a scatterer reflects an electromagnetic wave in a given direction. Simulation results obtained from MATLAB for the scattered field, the total field, and the radar cross-section are presented for three soil types – sand, loam, and clay.

Image Reconstruction with Acoustic Measurement Using Distorted Born Iteration Method

1996 ◽  
Vol 18 (2) ◽  
pp. 140-156 ◽  
Author(s):  
C. Lu ◽  
J. Lin ◽  
W. Chew ◽  
G. Otto
Keyword(s):  
Cross Section ◽  
Born Approximation ◽  
Measurement Data ◽  
Arbitrary Cross Section ◽  
Ultrasonic Measurement ◽  
Diffraction Tomography ◽  
Two Dimensional ◽  
Scattering Problems ◽  
First Order ◽  
Scattered Fields

The distorted Born iterative method (DBIM) is applied to solve electromagnetics and ultrasonics inverse scattering problems. First, we use the DBIM to process the data, which are the scattered fields from two-dimensional cylinders with arbitrary cross section. From this simulation, we confirmed that the first-order Born approximation can be applied to larger objects as long as the phase change of a wave passing through the object due to its presence is smaller than a limit. Then we applied DBIM to process the ultrasonic measurement data. Images for a balloon and an egg that are immersed in water have been reconstructed and compared with those from the first-order diffraction tomography (DT).

Diffraction of Pulses by Cylindrical Obstacles of Arbitrary Cross Section

1962 ◽  
Vol 29 (1) ◽  
pp. 40-46 ◽  
Author(s):  
M. B. Friedman ◽  
R. Shaw
Keyword(s):  
Shock Wave ◽  
Integral Equation ◽  
Cross Section ◽  
Analytical Solutions ◽  
Arbitrary Cross Section ◽  
Two Dimensional ◽  
Algebraic Equations ◽  
Dimensional Problem ◽  
Acoustic Shock Wave ◽  
Square Box

The two-dimensional problem of the diffraction of a plane acoustic shock wave by a cylindrical obstacle of arbitrary cross section is considered. An integral equation for the surface values of the pressure is formulated. A major portion of the solution is shown to be contributed by terms in the integral equation which can be evaluated explicitly for a given cross section. The remaining contribution is approximated by a set of successive, nonsimultaneous algebraic equations which are easily solved for a given geometry. The case of a square box with rigid boundaries is solved in this manner for a period of one transit time. The accuracy achieved by the method is indicated by comparison with known analytical solutions for certain special geometries.

Partially Invariant Solutions for Two-dimensional Ideal MHD Equations

1990 ◽  
Vol 45 (11-12) ◽  
pp. 1219-1229 ◽  
Author(s):  
D.-A. Becker ◽  
E. W. Richter
Keyword(s):  
Differential Equations ◽  
Linear Equations ◽  
Mhd Equations ◽  
Two Dimensional ◽  
Invariant Solutions ◽  
First Order ◽  
Partially Invariant Solutions ◽  
Quasilinear Systems ◽  
Ideal Mhd ◽  
Non Linear Equations

AbstractA generalization of the usual method of similarity analysis of differential equations, the method of partially invariant solutions, was introduced by Ovsiannikov. The degree of non-invariance of these solutions is characterized by the defect of invariance d. We develop an algorithm leading to partially invariant solutions of quasilinear systems of first-order partial differential equations. We apply the algorithm to the non-linear equations of the two-dimensional non-stationary ideal MHD with a magnetic field perpendicular to the plane of motion.

A Difference Method for Plane Problems in Magnetoelastodynamics

1972 ◽  
Vol 39 (3) ◽  
pp. 689-695 ◽  
Author(s):  
W. W. Recker
Keyword(s):  
Partial Differential Equations ◽  
Differential Equations ◽  
Numerical Method ◽  
Difference Method ◽  
Necessary Condition ◽  
Two Dimensional ◽  
Symmetric Hyperbolic System ◽  
Von Neumann ◽  
First Order ◽  
Independent Variables

The two-dimensional equations of magnetoelastodynamics are considered as a symmetric hyperbolic system of linear first-order partial-differential equations in three independent variables. The characteristic properties of the system are determined and a numerical method for obtaining the solution to mixed initial and boundary-value problems in plane magnetoelastodynamics is presented. Results on the von Neumann necessary condition are presented. Application of the method to a problem which has a known solution provides further numerical evidence of the convergence and stability of the method.

Long waves in a uniform channel of arbitrary cross-section

1968 ◽  
Vol 32 (2) ◽  
pp. 353-365 ◽  
Author(s):  
D. H. Peregrine
Keyword(s):  
Solitary Wave ◽  
Cross Section ◽  
Gravity Waves ◽  
Equations Of Motion ◽  
Rectangular Channel ◽  
Arbitrary Cross Section ◽  
Long Waves ◽  
Order Of Approximation ◽  
Two Dimensional ◽  
Uniform Channel

Equations of motion are derived for long gravity waves in a straight uniform channel. The cross-section of the channel may be of any shape provided that it does not have gently sloping banks and it is not very wide compared with its depth. The equations may be reduced to those for two-dimensional motion such as occurs in a rectangular channel. The order of approximation in these equations is sufficient to give the solitary wave as a solution.

Two-dimensional toroidal MHD equilibria of arbitrary cross-section

1983 ◽  
Vol 29 (1) ◽  
pp. 173-175 ◽  
Author(s):  
Ferdinand F. Cap
Keyword(s):  
Equilibrium Problem ◽  
Cross Section ◽  
Arbitrary Cross Section ◽  
Two Dimensional ◽  
New Approach ◽  
Mhd Equilibrium ◽  
Mhd Equilibria

A new approach to the solution of the MHD equilibrium problem is outlined.

Sign in / Sign up

Export Citation Format

Share Document